1. Field of the Invention
The present invention relates to an X-Y stage system with onboard linear motor, which has been extensively used in machinery including semiconductor and liquid display manufacturing equipment, measuring instruments, assembling machines, tool machines, industrial robots, conveyors and, more particularly, to an X-Y stage system with onboard linear motor in which an armature winding of primary side is installed on, for example, a turntable while a field magnet of secondary side lies on a stationary bed.
2. Description of the Prior Art
In recent years, current multi-axis stage systems and moving mechanisms such as X-Y plotters employed in the diverse technical fields using machinery as stated earlier have required more and more a position-control stage, which is made compact or slim in construction and light in weight, and moreover able to operate with high propulsion, high speed and high response to allow a moving object including works, tools, articles and instruments to move relatively to a machine base into any desired position with high travel speed and precise position control. Most X-Y stage systems of the sort as stated earlier have usually incorporated with a linear motor to drive either of an X-stage and Y-stage. Linear motors involve two broad types. The first, called moving-coil linear motor has a plurality of moving-armature windings. The second, called moving-magnet linear motor has many moving-field magnets of permanent magnet.
In Japanese Patent Laid-Open No. 266660/1997, which was filed for a senior invention of the same applicant as in the present application, there is disclosed an X-Y table system having solenoid-operated linear actuators. With the prior X-Y table system, armature windings for the primary side of the solenoid-operated linear actuators are laid in an intermediate moving member and connected electrically to an outside console through openings in the intermediate moving members while guide means are constituted with linear motion guide units of such sort as allowed to roll over only a definite travel by virtue of crossed-rollers. The table system recited just above can be considered to be a way to make the system itself compact or slim in construction.
Another Japanese Patent Laid-Open No. 2000-333435, also filed for another senior invention of the same applicant as in the present application, discloses a slider unit with onboard moving-coil linear motor, in which the field magnet of secondary side is made up of field magnet sheets lying on confronting surfaces of vertically opposing sides of a horseshoe-shaped magnet yoke sidewise open in cross section, the field magnet sheets being juxtaposed closely side by side in such a way that unlike poles alternate lengthwise in polarity and also oppose directly to each other across an air gap. The armature windings of primary side are each made of a three-phase coreless coil wound in the shape of rectangle. Many armature windings are disposed closely side by side on a coil support to complete the armature winding assembly, which extends into the air gap through the sidewise opening of the magnet yoke. With the prior slider unit recited earlier, the horseshoe-shaped magnet yoke of integral structure helps render the slider unit itself compact in construction.
Meanwhile, production systems linked with semiconductors, for example semiconductor manufacturing equipment, measuring instruments, assembling machines, and so on can advance greatly in years and correspondingly makes a growing demand for X-Y stage systems and angular position control stage systems that can operate with high precision, high speed, high propulsion, high response and clean environment, even with made far compact or slim in construction and far inexpensive in production cost, compared with the conventional slider unit.
With the prior X-Y stage system constructed as stated earlier, the field magnets of secondary side are arranged on the upper surface of the stationary bed and the lower surface of the Y-table, one to each surface, and therefore magnetic attraction exerted constantly between the field magnets and the coil yoke with the armature windings may causes any deformation on both the bed and the Y-table, which might account for any error in precision.
Thus, it remains a major challenge to provide a slider unit with onboard moving-magnet linear motor, which advances in conduction system for armature windings, selection of material for field magnet, selection of encoder high in resolving-power and fixture construction of sensor cords to make the slider unit nimble in operation, less in weight, compact and simple in construction, far more precise in position control as well as far more speedy in response of the X-Y table relatively to the bed, large in angle allowed for angular movement in circular direction upon position control, reduced in overall height as low as possible, and inexpensive in production cost.